PROJECT SUMMARY Myocarditis caused by viral infections is a leading cause of sudden death and can progress to dilated cardiomyopathy (DCM) and the need for a heart transplant. Currently, there are no disease-specific therapies to reduce myocarditis or prevent progression to DCM. Toll like receptor 4 (TLR4) is known to promote viral myocarditis, triggering proinflammatory cascades that promote acute heart failure and progression to DCM. Thus, there is a need to develop novel therapies that suppress TLR4-driven inflammation to ameliorate myocarditis. Recent studies have indicated that adipose-derived stem cells (ADSCs) have anti-inflammatory effects that are mediated by cell-secreted biogenic nanoparticles (BiNPs). However, the immunomodulatory properties of heterogeneous adipose tissue-derived BiNPs have not been explored. Our preliminary results indicate that adipose tissue-derived BiNPs: (i) suppress TLR4-induced inflammatory responses in macrophages, (ii) reduce inflammation and TLR4 expression in a mouse model of viral myocarditis, (iii) take less time to process, cost less to obtain, and are more abundant compared to cell culture-derived BiNPs, and (iv) can be loaded with conventional drugs that further enhance anti-inflammatory effects. We hypothesize that adipose-derived BiNPs reduce TLR4-induced activation of inflammation in the heart and can be used to treat myocarditis and DCM. To test this hypothesis, we will determine the mechanism of patient-derived lipoaspirate- derived BiNPs (Lipo-NPs) in a mouse model of myocarditis/ DCM (Aim 1), and assess the performance of patient-derived Lipo-NPs as drug delivery vehicles for anti-inflammatory compounds in a mouse model of myocarditis (Aim 2), measuring the biodistribution of Lipo-NPs in healthy and male and female mice with myocarditis and determining the effect of Lipo-NPs loaded with anti-inflammatory agents on myocarditis by sex. We will utilize our laboratory's expertise in BiNP isolation along with a well-characterized murine viral myocarditis/ DCM model. We anticipate that this study will delineate the role of adipose BiNPs in myocarditis/ DCM and potentially lead to new clinically relevant therapeutic strategies.